partícula beta

The Environmental Protection Agency has set National Ambient Air Quality Standards for particulates. One, in effect since 1987, regulates particles smaller than 10 microns in ...

enfermedad endémica

Anthropology; Physical anthropology

A disease that remains at a more or less constant frequency of affected individuals in a population all of the time. Examples: hypertension, tooth decay, and malaria.

polimorfismo

Anthropology; Physical anthropology

A genetic trait controlled by more than one allele, each of which has a frequency of 1% or greater in the population gene pool. See balanced polymorphism.

termoluminiscencia (TL)

Anthropology; Physical anthropology

A radiometric dating method based on the fact that trace amounts of radioactive atoms, such as uranium and thorium, in some kinds of rock, soil, and clay produce constant low ...

modelo de asimilación

Anthropology; Physical anthropology

A hypothesis to explain the origin of modern Homo sapiens. It proposes that the first modern humans evolved in Africa, but when they migrated into other regions they did not ...

potasio-argón

Anthropology; Physical anthropology

A radiometric dating method based on the fact that potassium-40 in volcanic rock decays into argon-40 and calcium-40 at a known rate. The half-life of potassium-40 is ...

pedernal

Anthropology; Physical anthropology

A kind of hard, rock with a glassy opaque appearance. It was a favorite raw material for many prehistoric humans for the manufacture of tools such as knives and scraping ...